Kennedy moved from Boston to Decatur to work for Archer Daniels Midland in the 1980s, and has spent his life working around issues of hunger, whether as the chairman of the Greater Chicago Food Depository, or now helping to run the non-profit he and his wife founded, Top Box Foods.[10]

Kennedy was the president of Merchandise Mart Properties in Chicago, Illinois, from 2000 until 2012. The property was originally owned by the Kennedy family until it was sold to Vornado Realty Trust, a real estate investment trust. The Merchandise Mart, one of the properties of Merchandise Mart Properties, is the largest commercial building in the world, serving as both a luxury wholesale design center and one of the leading international business locations in Chicago. The Mart spans two city blocks and rises twenty-five stories for a total of 4.2 million square feet (390,000 square metres) Three million people come through the Mart each year to visit its retail shops, permanent showrooms, and office space as well as attend the numerous trade, consumer and community events hosted there.

In May 2012, Kennedy started the Chicago-based non-profit Top Box Foods. The organization was created as a way to get discounted groceries to families who live in areas that either lack grocery stores or have an abundance of fast food. Kennedy initially invested $150,000 to get Top Box started, and subsequently designed the organization to be self-sustaining.

Top Box as an organization purchases food, boxes it in various combinations and delivers it monthly to churches and organizations in mostly low-income neighborhoods. The food items in the box change from month to month and include a wide variety of fruits, vegetables, meats, and frozen meals, with box prices ranging from $19 to $39. The boxes can be ordered online or through the organizations where the boxes are delivered. These organizations, otherwise known as Top Box "host sites," range from small neighborhood churches with a few dozen families to some of the Chicago's largest, including Trinity United Church of Christ and Salem Baptist Church.

Kennedy met Sheila Sinclair-Berner (born December 4, 1962), an Illinois native, while attending Boston College. After graduating from college in 1986, Kennedy moved to Decatur, Illinois, and married in 1987.[12] The couple had four children, Katherine Berner "Kate" Kennedy (1990-, Christopher George "Chris" Kennedy, Jr. (1992-, Sara Louise Kennedy (1994-, and Clare Rose Kennedy (1998-, whom they are raising in the Chicago suburb of Kenilworth. His wife earned a law degree from Northwestern University and practiced at Sidley & Austin[citation needed] in Chicago before taking time off to take care of their children.

The National Journal once quoted Kennedy as saying, "I have a lot to keep up with: a brother who might run for Congress, a sister and a brother considering races for governor, a cousin who might run for Congress, another in Congress, an uncle in the Senate and a cousin-in-law, Arnold[Schwarzennegger], who is thinking of running for governor."[13]

Beyond his family, Kennedy has served in a variety of capacities for numerous political campaigns, including hosting a fundraiser for Barack Obama in his bid for U.S. Senate.[citation needed]

Prior to February 8, 2017, when Kennedy announced his candidacy for the Democratic Nomination for Illinois Governor in 2018,[18] he had never run for any elective office.[16]

Kennedy during his campaign for governor advocated for “a property tax system that can’t be abused by the wealthy and insiders” in a fundraising email.[19] Kennedy criticized one of his fellow Democratic gubernatorial candidates, J.B. Pritzker, for getting a large property tax reduction on a Gold Coast mansion.[20] “It’s an inherently corruptible system and we ought to reject it,” Kennedy said to reporters in reference to Pritzker’s property taxes.[21] "The Cook County property tax appeals business is notorious for pricing political connections at a premium," wrote the Illinois Policy Institute, a conservative website.[22] Kennedy has further gone on to state that what Mike Madigan is doing, referring to his conflict of interest from serving as the house speaker while working as a property tax attorney, should be illegal.[23]

Kennedy called for an open primary in the 2018 gubernatorial race, urging the Cook County Democratic party not to throw their weight behind any other candidate, instead allowing for voters to vet all the candidates in the race.[25]

Since 2000, Kennedy has been a member of the City Club of Chicago, a group that brings together civic and cultural leaders to discuss and debate issues affecting the Chicago area.

Since 2005, he has been a member of the Commercial Club of Chicago, a group that brings together the city's business, educational, and cultural leaders on projects to improve central industries and create new economic opportunities.

Greater Chicago Food Depository is a nonprofit food distribution and training center providing food for hungry people while striving to end hunger throughout Cook County, Illinois. It also offers education programs providing the knowledge and tools needed to break the poverty cycle.

El Valor[29] is a nonprofit group seeking to enrich the local community by empowering the underserved, disenfranchised, and disabled while creating a sense of unity among all community members.

As Chairman of Joseph P. Kennedy Enterprises, Inc., Kennedy is responsible for the development of the Kennedy family real estate holdings in Chicago known as Wolf Point, Chicago. The Wolf Point development site represents a billion-dollar commitment to the downtown core, and the site is zoned for construction of a residential apartment building, a self-park garage, and two additional high-rise buildings.

Kennedy also is a partner in Sudbury Station LLC, a development entity proposing a 250-unit luxury rental housing development with a state mandated minimum affordable housing set aside in Sudbury, Massachusetts, designed to meet local housing needs for seniors and the working class community. Proposed on a 39-acre parcel zoned residential near the Historic District of Sudbury, the Village at Sudbury Station would satisfy the Massachusetts affordable housing mandate for Sudbury, would be located close to schools, parks, churches and public safety facilities, and would contribute significant additional tax revenue to the town.[32][33] The project has received widespread criticism from town officials and residents. Residents voted unamiously to hire a special counsel to stop the development, which violates over thirty local zoning ordinances.[34][35]